For mass production, a convenient design for an uninterruptible power supply (UPS) is to have identical “building block” that are used over and over again to get the desired power level. This is similar to a modular UPS construction where each building block is a functional UPS which are in turn parallel connected to get the desired power level. In a modular UPS design, the control system is distributed in each building block. It would be preferable to employ a centralized controller that controls each building block.
Each building block, however, requires slightly different control signals to account for differences in each building block. For example, each building block contains inductors and capacitors and these components having manufacturing tolerances ranging from ±5% to ±10%. From a centralized controller, if the same control signal is applied to each building block, the power through each building block will be different due to the mismatch in components (i.e., inductors and capacitors). In one approach, the inductors, capacitors and other building block power components can be oversized to account for any anticipated mismatch between components. Unfortunately, this approach adds cost. Therefore, there is a need for centralized control that balances power in each of the building blocks of a UPS.
This section provides background information related to the present disclosure which is not necessarily prior art.